Pulse regenerator



Aug 24, 1943- y oD SHEPHERD 2,327,465

PULSE REGENERATOR /A/VENTZOR JUS ON 0'0. SHEPHERD gimme@ A 7` TORNE VAug. 24, 1943. v J, o'D SHEPHERD 2,327,455

PULSE REGENERATOR Filed July 11, 1941 7 sheets-sheet 2 COMMON COMMON A CTUA TOE MA GIVE 715 47 /VVE/Vm/Q Juoso/v on SHEPHERD BMWMWM? ATTO/Q [YAug- 24, 1943- v J. OD SHEPHERD 2,327,465

PULSE REGENERATOR 1 /M/ENTOR JUDSlQN 00. SHEPHERD 55m-c roe :EL Ecroa MAGNET MA @NE 7 'ATTORNEY Aug 24, 1943 J. AOD SHEPHERD 2,327,465

PULSE REGENERATOR Filed July 11 ,l 1941 '7 Sheets--Slleexl 4 coMMo/vAcn/,q rola MEGA/E7 o 2 o 33 a 6? a a/ 3 o- 4 7 7 z v 46 Ja2 79RELEASE 27 MA G/vEr a 7a 29 69 o 68 5 Q s o /N-puL sE ou T-PuLsESELECTOR SELECTOR MAGNET MA e/vE r //VENro'R JUDgQN OI. SHEPHERD wwwATTORNEY Aug 24, 1943- J. oD SHEPHERD 2,327,465

PULSE REGENERATOR Filed July ll 1941 7 ShHELS-Sheet 5' /N-PULSEOUT-PULSE CTUATOR SELECTOR MAGNET MAGNET MA G NE T AT TORNEV All@ 24,1943 J. oD SHEPHERD Y 2,327,465

PULSE REGENERATOR Filed Ju1y11, 1941 7 sheets-shet e RELEASE MAGNETlN-PULSE OUT-PULSE SELECTOR SELECTOR. MAGNET MAGNET ATTORNEY Aug., 24,i943. J. oD SHEPHERD 2,327,465

PULSE REGENERATOR Filed July 1l 1941 'T Sheets-Sheet 7 F/G /8 IVI/VORSW/TCH .9/ STEPP/NG M4 N57' MTL Il@ n@ M/NOE SWITCH RELEASE COMMON A CTUA T/ MA GNE T MA GNE T RELEASE MAGNET IIHII N OUT-PULSE .saft To@ MAGNE T I SEQUENCE `5`W/TC`H MAGNET /M/EA/TOR JUDSON O'D. SHEPHERD A TTOR/VE V Patented Aug. 24, 1943 UNITED STATES' PATENT OFFICE PULSEREZGENERATOR Judson OD. Shepherd, Atlanta, Ga.

Application July 1l, 1941, Serial No. 401,914

t Claims. V(VCI. 177-353) This invention relates to pulse regeneratorsof l i the register sender type comprising essentially a mechanicaldevice which is used as a link in an electrical circuit for relayingelectrical effects.

The object of the invention is to provide a simple and economicalmechanical device which will respond to incoming electrical effects andthereafter control the transmission of outgoing electrical eiiects. Inone form the incoming and outgoing electrical effects will be identicaleX-,

cept in what may be termed purity. Such a device is particularly usefulin long signaling circuits where due to the length and condition of thetransmission circuit the incoming signals may be distorted both in timeand strength..l

Such a device will then respond to such signals and thereupon transmitregenerated or corrected signals. The device in a preferred embodimentherein disclosed is useful in a telephone system for the regeneration ofswitch setting pulses-v4 which are usually transmittedon a decimalbasis,

spoken of as trains of digitalpulses. In this form the device respondsto a train of pulses by translating such train into a code and operatinga set of mechanically displaceable elements-alsof in code. Thereafterthe device operates to be in position to aifect another set ofdisplaceable elements corresponding to a succeeding train of pulses.

Aiter a number of sets of displaceable ele-.1,

ments corresponding to the number of digits are set and depending on thetype of start circuit employed, a detector and outgoing pulseYconr`clier is placed in operation. This moves a set ci detectorcontacts into association with thej first set of displaceable elementsand correspending contacts are closed by the displaced Release isaccomplished by moving both theY detector mechanism and the displaceableelement operating mechanism to normal.A The latter, carrying a cammingmember, restores all displaced elements to normal in its sweep back tonormal. In order to fully accomplish this function this displaceableelement operating mechanism moves back to a point a steprbeyond theposition where it is associated with the first set oi such elements andis thereupon immediately moved forward until it is in such position. Thedetector moves back to a normal position one step beyond the positionwhere it is associated with the iirst set of displaceable elements.

In another embodiment of the invention the sets of displaceable elementsmay be set under ,keyboard control rather than in response to incomingdigital trains of impulses and thus may serve as a key-pulsing sender.

ln another embodiment the outgoing electrical efect instead of being inthe form of digital trains of pulses may be in the form of othersignals, to operate, by way of example, a call indicator.

A feature of the invention is an arrangement including a plurality ofsets of mechanically displaceabie elements, a mechanical displacingmeans movable into association with said sets separately and amechanical detector also mov- Y able into association with said setsseparately.

A feature of the invention by which the present device diiiers fromknown arrangements is the use of sets or" displaceable elementspermanently positioned and associated with movable setting and movabledetecting means.

Another feature of the invention resides in the f restoring means bywhich the individual disi scription.

The drawings consist of seven sheets having eighteen figures as follows:

Figure l is a side elevation in diagrammatic form of the essentialelements of the device of the present invention, in normal idlecondition;

Fig. 2 is a plan View of the same, taken as indicated by the broken line2--2 in Fig. l;

Fig. 3 is a` fragmentary View of the device .taken as indicated by thebroken line 3 3 in Fig. :1;

fthe in-pulse off-normal contacts after the inpulse selector arm hasbeen advanced;

Fig. 8 is a similar view showing the position of the in-pulse off-normalcontacts during the restoring kmovement and at the time the in-pulseselector arm has reached its eXtreme position in its clockwise movementand before it has been automatically stepped one step forward to itsnormal position;

Fig. 9 is a fragmentary View of the overtake switch arm in its normalposition as indicated by the broken line Q in Fig. 3;

Fig. l is a fragmentary side elevation sho-w-` ing one switch settingmagnet operated and another in normal position to illustrate them'annerin which the separate displaceable elements of a set may be operated;

Fig. 11 is a fragmentary top view used in conjunction with Fig. toillustrate the manner of v vanced into cooperative relation with the rstset of dsplaceable elements;

Fig. 14 is a fragmentary top view taken along` the broken line lll-lliof Fig. 13 illustrating how the switches of the out-pulse selector armare operated by displaced elements;

Fig. 15 is a fragmentary side view showing the action of the releasemagnet;

Fig. 16 is a fragmentary side View showing the iii-pulse selector arm'just one step ahead of the out-pulse selector arm and illustrating themeans by which the overtake switch is operated;

Fig. 17 is a fragmentary top View used in conjunction with Fig. 16 toillustrate the manner' in which the overtake switch is operated; and

Fig. 18 is a circuit diagram of the velectrical connections throughwhich the apparatus of the previous guresis used for the purposesandobjects of the invention.

For the sake of clarity the greater part ofthe frame on which thevarious elements of this device are mounted has been omitted, but 'itwill be understood that a suitable frame is provided which will hold thevarious parts secured in the positions shown. The web I may beconsidered part ofthe frame and the part if. von which'contacts S and iare mounted are part. of thesame frame. ous magnets such as 5, 'i and ilare secured to the frame. In the following description it. will beunderstood that other immovable parts such Also it will be understoodthat tie vari-2v Ysition by the spring Bil.

` given set4 of' displaceable elements.

with the exception of the i-lf th element, is formed in such a mannerthat it will remain in either its normal or its operated position underthe iniiuence of a coiled spring. In Fig. 13 the displaceable element 2is shown held in its operated position by the spring 23 and thedisplaceable element 29 is shown held in its normal po- The springs 3|and 32 in Figs. le and 17, respectively will indicate. how these:retaining springs are mounted and secured to the'frame piece i2.

When the device is in its normal position as indicated'in `rlig. l, eachdisplaceable element of each set vis in the position of element 29 shownin Figf, for example. At this time the in-pulse selector arm isincooperative relationship with the rst set'of felem'ents i3. Eachelement in t-hisset is then under control of one ofthe magnets to H. Ifthe magnet' is energizedthen 'by attracting its "armature it will move"an arcuate 'common actuator v33 in the Imanner indicated in Fig.l'oai'idca'use the element ES to' assume the position shown inFigplB.

The 'in-pulse vselector arm andthe out-pulse `selectorarm arero-tatabieeleme'nts by -means of Ywhich the circuit arrangement 'to behereinafter 'described may be-operatively associated with any Rigidly`secured to the frame l andiits companion piece 134 isa'shaft on-which'thel rotatableselector `arms are mounted.

Thein-'pulse 'selector' arm compri-ses the two carries a set of links,4), 4 i and 42, as may ybest l be seen'inFig. 1l,A which1serve'asoperating links between thea'rcuate common actuators 3.3;l43,44

and Q5, respectvelygand the -corresponding displaceable 'elementswithwhi'chthe in-pulse selector arm has cooperativelyr associated them.Each yflink isin'theform of a'plunger'normally retained in a directionto tend to bear upon its associated varcuate common actuatorby a-'springsuch as the springd associated with the 4link-'39,sho'wn vby Figs. 53nd13.

The in-'pulseselector arm 33', at the end thereof "where it'is mountedontheshaft 35,is formed into the various'setsof displaceable elements.

a ratchet'wheelsector 4l'. A p'awl 43 operated'by thein-pulsemagnet 5cooperates with this ratchet wheelsector Lilitomove the in-pulseselector arm step by'step `intofcooperative relationship with Ados "4Ssecuredtoan element 'Edforming part' ofthe 'frame'will act' to 'retainthe inlpuisev selector 'arm Jin any1 pcsition'to' which it has'be'enmoved.

as the indicated anchorages for the retractile springs for holding thearmatures of these magnets are also appropriately secured to the frameeven where mention of this fact has been omitted. Y

YThe device consists essentially of an arcuate shaped frame member i2 inwhich a plurality of f. sets of displaceable elementsV are mounted. The

`a fth displaceable element such as 25 associated with each set of suchelements which operates in a different manner as wil-l appearAhereinafter. Each elementof the sets of displaceable elements C Theout-pulse'selector varm is provided 'with a iratchet" wheel4 sector E3similar Ito the 'ratchet wheel sector 3 which is under control of apawl5i 'operated-by the out-pulse magnet 6. Y"Ratchet "wheel 's'e'ctor53 isvmaintained" in the positionto "whichit is'rnoved byl aI dog 'I I5similar in func- `tion to dog' 139. '.Arelease cam y52 is rotatablymountedon the shaft 35 between the 4ratchet l`sector12T/and' the'ratchet 'sector 53 vof the outpulse selectorfarm. The release camS'Zoperated 'by the release magnet'liwillengage bothl pawlsf'48 "and 5!andthe dogs and Hand` lift them out of engagement' with the teeth of theratchet "sectors '47 vand 53'a'nd allow the'in-pulsesele'ctorarmtoireturn toriormal under' the' influenceof I-spring 54 andtheout-pulse Yselectora'rm to return 4"t'onormalf under the influence ofspring.

terminates at the shaft 35 in a ratchet Wheel sector 41, sothearm 31terminates in an element t provided with an integral cam formation 51.In the normal position of the in-pulse selector arm (Fig. 6) and thesubnormal position thereof (Fig. 8) in which it remains only for aninstant, the cam 51 causes the in-pulse oif-normal contacts 53 and 59 toopen an associated circuit therethrough. In these two positions the cam51 engages a cooperating cam on the spring 60 which lifts the contactspring 58 away from the spring 55. In all other positions of thein-pulse selector arm the associated circuit is closed through thesprings 53 and 59.

Movement of the in-pulse selector arm in its releasing movement beyondthe subnormal position indicated in Fig. 8 is prevented by a stop Elwhich is part of the frame.

An element 52 in the form of a bar is secured to the arms 36 and 31.This bar carries four cams 53, 55, 65 and 66 which cooperate with thedisplaceable elements and act to return them to their normal positionson the return movement of the iii-pulse selector arm. 'Ihese cams arealways associated with the neXt set of displaceable elements in orderfrom the set upon which registration is taking place. For instance, whenthe inpulse selector arm is in cooperative relationship with set I3, therestoring cams are in association with set l'I. For this reason on therestoring movement of the in-pulse selector arm this arm is caused tomove one step beyond its normal position to a subnormal position fromwhich it is immediately returned one step forward automatically. Due tothis temporary movement into a subnormal position the restoring cams arebrought into association with the first set of displaceable element I3to restore any displaced elements thereof t-o normal.

The element 38 also carries a cam 51 which is used for the purpose vofoperating an overtake switch. There is a spring returned plungerassociated with each set of displaceable elements which is movedwhenever the in-pulse selector arm is associated with such set ofelements. Thus the plunger 68 is associated with the set of elements I3,consisting` of elements 21, 53, 1I) and 'il (Fig. S) It will appearhereinafter that when the out-pulse selector arm moves into position onestep behind the in-pulse selector arm that the operated plunger 68 (or acorresponding one) will cause the operation of the overtake switch sothat the two selector arms cannot at the same time be associated withthe same set of displaceable elements.

The cut-pulse selector arm consists essentially of a U-shaped member 12,best seen in Fig. 3, on which four sets of detector contact springs-associated individually with springs 13, 14, and 16 are mounted as wellas the overtake switch. This member 12 terminates in two parts by whichit is rotatably mounted on the shaft 35. One of such parts constitutesthe ratchet sector 53 while the other becomes a simple bearing element11. The ratchet sector is provided with an arm'18 (Figs. l2 and 13)which in the normal position of the out-pulse selector arm moves thespring 1S to cause the associated circuit through the out-pulseofi-normal contacts 3 and 4 to open. In all other positions of theout-pulse selector arm the said associated circuit is closed. A p-ortion85) of the frame acts as a stop to prevent this arm from moving backwardbeyond itsnormal position.

Each set of detector contact springs comprise ing a detector switchconsists of a spring such as 13 (Figs.. 3 and 14) provided with a cam 8|mounted on the end thereof-and arranged. to cause a circuit throughsprings B2 and 83 to become closed. When the out-pulse selector armmoves into association with a set of displaceable members each detectorswitch associated with a displaced member will be operated, 4as clearlyindicated in Fig.Y 14.

Also mounted on the bar 12 (Fig. 3) is the overtake switch assemblyconsisting of a mounting 84 carrying a spring plunger 85 arranged tomove the spring 86 to cause the opening of the associated circuitthrough the contact springs 81 and 88. A cam 89 is mounted on the end ofthe spring plunger 85 for the proper mechanical cooperation of theplungers 85 and 58 as will be apparent particularly in Figs. 3, 9, 16and 17. This overtake switch is mounted so as to be in association withthe Vset of displaceable elements ahead of the set with which theoutpulse selector arm is associated so that when the latter approacheswithin one set of the position of the in-pulse selector arm it will beprevented by means controlled by the overtake switch from advancinguntil the in-pulse selector arm has taken another step.

The registration of a series of trains of impulses is eifected bydepression of a combination of elements 22 to 25 in each of sets I3 to'2| in order. The control circuit for the device, as will hereinafter bedescribed, will cause the operation of one or more registration magnets8 to I I in accordance with a predetermined code upon receipt of thefirst train of impulses. This will result in the operation of one ormore of the four common actuators 33 to depress a corresponding elementcr elements 22 to 25 of the first set I3. Upon release of thisregistration magnet or magnets, the irl-pulse portion of the device,including member I2, is advanced to the set of elements I4 by magnet 5.Receipt of the second train of pulses will result in correspondingregistration Y thereof in set Iii, and the subsequent advance to set I5.This is repeated until all trains of pulses are registered.

When the rst train of impulses has been registered and the member I2 hasadvanced to set I4, the overtake contacts 31 and 83 are closed to signalthe control circuit that a train of pulses may be transmitted beyond.The out-pulse portion is then advanced one step to where detectorcontacts S-'IG may be actuated by any elements '2z-25 in row I3 whichmay have been displaced. The lactuation of one vor more of the lattercontacts will complete a circuit or combination of circuitscorresponding to the code of the first train of impulses. Thiscombination is decoded, as will be described and transmitted beyond. Ifthe in-pulse portion has, in the meantime, advanced to set I5, theout-pulse portion will ad- Vance after a brief interval to set I3,decode the registration thereon, and transmit the corresponding trainbeyond. This is repeated until all registered trainsV have beentransmitted. The contacts 81 and 88 are opened to prevent furtheradvance of the out-pulse portion whenever it reaches a set of contactsjust back of those with which member I2 is engaged. In some applicationsof the device, the start of the out-pulses may be delayed until theentire number has been registeredror a start signal is furnished theoutpulse portion that it may begin transmission of the registration.

When the device is to be released, release magnet 1 will be operated toraise the pawls and Magnet 6 is deenergized and a circuit for theautomatic return of the sequence switch'to its normal position isclosedV through armature and back contact of relay |06 and sequenceswitch cam H4.

If the overtake switch is still closed the next digitwill be transmittedin the same manner but if the overtake switch is open the transmissionof the next digit will await the advance of the in-pulse selector arm.

When the subscriber releases the connection and relays 9i and 92 areboth returned to normal a circuit from ground will be extended throughthe armature and back Contact of relay 9|, armature 4 and back contactof relay 92, thence in parallel through the out-pulse ofi-normalcontacts 3 and 4 and the in-pulse off-normal contacts 58 and 59 to therelease magnet l. This will allow the out-pulse selector arm to returnto normal and the inpulse selector arm to move to its subnormalposition.

It will be noted that Ythe lower winding of relay S4 is in parallel withthe release magnet 1. Hence the in-pulse selector magnet 5 will beenergized during the energization of the release magnet l. The relay 94is slow to release and hence the magnet 5 is still energized when therelease magnet becomes deenergized so thatthe pawl 48 will drop into anadvanced tooth of the ratchet sector 4l. Upon the release of relay ySiland the following release of magnet 5, the inpulse selector arm isadvanced from its subnor mal to its normal position and the apparatus isready to function again.

It should be noted that the overtake switch s contacts 81 and 88constitute a start control means. As the circuit arrangement is shownthe out-pulsing will start as soon as the registration of the firstdigit has been completed. There may be other uses of this apparatus inwhich the outpulses are not( wanted until more than one train ofin-pulses have been registered or until all of l the trains of in-pulseshave been registered or in other cases until some predetermined time oreven in response to some outside operation.V In any of these cases anywell-known start control could operate another pair of contacts similarto and in series with the contacts 81 and 88.

It will be obvious that many other equivalent means may be employed forthe specic elements of the present invention. By way-of eX- ample itwill be recognized that a code drum such as that shown in my copendingapplication Serial No. 393,745, filed May 16, 1941 may be used as ameans for moving the actuators such as 33 so that the minor switch andthe selector magnets 8 to Il may be eliminated. In another arrangementthe magnets 8 to H may be operated through a set of keys in the mannerset forth in my said copending application. Other arrangements whichwould readily occur to one skilled in the art are embraced within thespirit of this invention.

What is claimed is:

1. A device comprising a plurality of sets of mechanically displaceableelements mounted in a iixed frame, a set of common actuating members,one for each element of a set, electromagnetic means including a Vgroupof magnets fixed with respect to said frame for operating said members,a set of links for transferring the operation of said members to thesaid mechanically displaceable elements of one of said sets at a time,means for moving said links into association with each of said sets ofmechanically dis- CII placeable elements, a detector comprising aplurality of sets of contacts equal in number to the number ofdisplaceable elements in each of said sets, each set of contacts adaptedto be operated by a corresponding displaced element when said detectoris associated with a particular set of said elements, means for movingsaid detector into association with each of said sets of mechanicallydisplaceable elements, and signaling means controlled by said detector.

2. A device comprising a plurality of sets of mechanically displaceableelements mounted in a fixed frame, a set of common actuating members onefor each element of a set, electromagnetic means including a group ofmagnets fixed with respect to said frame for operating said members, aset of links for transferring the operation of said members to the saidmechanically displaceable elements of one of said sets at a time, meansfor moving said links into association with each of said sets ofmechanically displaceable elements, a circuit arrangement responsive toincoming trains of digital pulses for Controlling said electromagneticmeans and said means for moving said links into association with each ofsaid sets of mechanically displaceable elements, a detector comprising aplurality of sets of contacts equal in number to the number ofdisplaceable elements in each of said sets, each set of contacts adaptedto beoperated by a corresponding displaced element when said detector isassociated with a particular set of said elements, means for moving saiddetector into association with each of said sets of mechanicallydisplaceable elements and signaling means controlled by said detector.

3. A device comprising a plurality of sets of mechanically displaceableelements, a set of common actuating members one for each element of aset, electromagnetic means for operating said members, a set of linksfor transferring the operation of said members to the said mechanicallydisplaceable elements of one of said'sets at a time, means for movingsaid links into association'with each of said sets of mechanicallydisplaceable elements, a circuit arrangement responsive tolincomingtrains of digital pulses for controlling said electromagnetic means andsaid means for moving said links into association with each of said setsof mechanically displaceable elements, a detector comprising a pluralityof sets of contacts equal in number to the number of displaceableelements in each of` said sets, each set of contacts adapted to beoperated by a corresponding displaced element when said detector isassociated with a particular set of said elements, means for moving saiddetector into association with each of said sets of mechanicallydisplaceable elements, signaling means controlled by said detector, andmeans controlled by said signaling means for controlling said means formoving said detector.

4. A device comprising a plurality of sets of mechanically displaceableelements, a set of common actuating members one for each element of aset, electromagnetic means for operating said members, a set of linksfor transferring the operation of said members to the said mechanicallydisplaceable elements oi one of said sets at a time, means for movingsaid links into association with each said set of mechanicallydisplaceable elements, a circuit arrangement responsive to incomingtrains of digital pulses for translating said trains of pulses into apermutation code for operating said electromagnetic means in ac-`cordance-With` said code and for controlling said means for moving saidlinks into association with each of said sets of mechanicallydisplaceable elements, a detector comprising a plurality of sets ofcontacts. equal in number to the number o-f displaceable elements ineach of said sets", each set of contacts adapted to beoperated by ancorrespending displaced element when said detector is associated'with aparticular-set of; said elements, means for moving said detector intovassociation with each of saidsets of mechanically; displaceable elementsand signaling means controlledA by said` detector.

5. A device comprising a plurality ci setsof mechanically displaceableelements, a set of common actuating members one for each element of aset, electromagnetic means for operating said members, a set of linksfor transferring, the operation of said members to thesaid mechanicallydisplaceable elements of one of said sets at a time, means for movingsaid'links into association Withsaid sets of mechanically displaceableelements in order beginning with a rst set which marks the normalposition of said lin-ks, a circuit. arrangement responsive to incomingtrains of digital: pulses for controlling said electromagnetic means andsaidV moving means, a detector comprising a plurality of sets ofcontacts equal in number to the number'of displaceable elements in eachof said sets,v each set of contacts. adapted to be operated by acorrespondingdisplaced element when said. detector is associated with aparticular sst of said elements; means for moving saiddetector intoassociation with each of said sets of mechanically displaceable elementsin order beginning from a stepI before said first set which said pointmarks tbe'ncrmal position of saidfdetector, signaling means controlledbysaid detector, and means for rel-easingV said moving means` and saidldetector to then" respective normal positions. Y

6. A device comprisingI a plurality of sets. of mechanically`displaceable elements, a set Ofcommoir actuating members one foreachelement of a set, electromagnetic. means for operating said n'iembersr,`a set of links forl transferring the operation of said members to:the-:said mechanically displaceable elements ci one; of said'sets at a'time, means forf movi-ng said links into association with said' sets ofmechanicallyV displaceable elements in order beginning with a iirst setwhich marks the normalposition of said moving means; a circuitarrangement responsive tof incoming trains of' digital pulses forcontrolling said' electromagnetic means. and saidl moving means, adetector comprising a plurality of sets of contacts equal in number tothe number-ofi displaceable.` elements in` each of saidsetsieacn set of'contacts adapted to: be operated by a corresponding displaced elementwhen'. said: detector is associated' with a particular set of said ele'-ments, means for moving said detectorI into-association with each ofsaid setsof mechanically d-isplaccablel elements-in' orderb'egin-ning;with a step before said: first setI which said point marks thefnorma-lposition of said detector, signal-ing means controlled bysaid'd'etector; means` for releasing saidmoving' means for said links;vand' for said: detectorto their respective normal positions, and meanscarried; by said moving meansfor said links. forY restoring alldisplaced elements during the return of said last moving meansv tonormal.

7. A device comprising a plurality of sets of mechanically displaceableelements, a set of common actuating members one for each element of aset, electromagnetic means for operating said members, a set of linksfor transferring the operation of said members to the said mechanicallydisplaceable elements of one of said sets at a time, means formovingxsaid links into association with saidsets` ofmechanicallydisplaceable elements in order beginning with a iilst setwhich marks the normal position of said moving means, a circuitarrangement responsive toincoming trains of'digital pulses for con.-troll-ing said electromagnetic means and said moving means, adetectorcomprising a plurality of sets of contacts equal in number tothe number of displaceable elements in each of said sets, each set ofcontacts adaptedY to-be operated by a correspondingdisplaced elementwhen said detector is associated with a particular set of said elements,means for moving said detector into association with each oi said setsof mechanically displaceable elements in older bcginning with. a-stepbefore said first set which said point marks. the normal position oflsaid detector, signaling means controlled by said detector, means forreleasing said moving means for said detector toY the normal positionoi'said detector and releasing said moving means for said links to aposition below'its normal position, meansk for thereupon automaticallymoving said last moving means to its normal position, means carried bysaid last moving means for restoring all displaced elements during thereturn of said moving means to its subnormal position.

8. A device comprising a plurality ofsets of mechanically displaceableelements, a set of common actuating members one for each element; of aset, electronfiagneticy means' for operating said members, a set'oilinks for transferring the operation of said members'to thesaidmechanically displaceable elements of one of saidsets` at a time, meansformoving saidlinks into association with said sets of mechanicallydisplaceable elements in rotation beginning Withl a rst'set which marksthe normal position of said moving means, a circuitarrangementrespon'sive to incoming trains' of digital pulses forcontrolling said electromagnetic means andA said moving means, adetector comprising a plurality of' sets of contacts ecualin number tothe number of displaceableY elements in eacli of said' sets, each set ofcontacts adapted to be operatedby a corresponding displaced element whensaid detector is associated Witlia particular set of elements', meansfor movingsaid detector into association with each of said sets ofmechanically displaceable elements in rotation beginning with a step'before said rst set which said` point marks the normal position of saiddetector, signaling inea-ns controlled by said detector, arelease-*magnet'for releasing said moving means andl said detector tothe normal position of said detector and means controlled by said movingmeans and detector upon their release to move said'V moving means asingle step forward from the normal position of said detector to thesaid normal position of said moving means.

JUDSON OD. SHEPHERD;

